1. Field of the Invention
The present invention relates to a semiconductor device and, more particularly, to a semiconductor device having a data output buffer circuit controlled by an output control signal, in which output noises attendant on data outputting operation of the data output buffer circuit do not affect the operation of other related input circuits.
2. Description of Related Art
Conventionally, for driving an external circuit, a semiconductor device of the type to which the present invention relates utilizes MOS field effect transistors (hereinafter referred to as "FET"s) in a data output buffer circuit. The data output buffer circuit also comprises an inverter, a NAND gate and a NOR gate. The data which is read out from an internal storage cell in the semiconductor device and amplified is outputted to the external circuit under the control of an output control signal. Such a conventional semiconductor device suffers from a problem such that, when the data is outputted, a transitional change (hereinafter referred to as an "output noise") in the power supply potential or the ground potential is unavoidably transmitted to other related circuits constituting the semiconductor device. Transmission of such an output noise occurs because a power supply line and a ground line connected to the data output buffer circuit are respectively in common with a power supply line and a ground line for other related circuits such as an external signal input circuit. This was a defect in the device since such an output noise had to cause changes in the input threshold voltage. An example of such a problem is that the logical level of the external input signal was inverted due to the influence of the output noise on the circuit.